Real Time Communication

metaJun 22, 20263 min readCurated summary

Adopting AV1 for Real-Time Communication (RTC) at Scale

Meta’s adoption of AV1 for real-time communication has been a multi-year effort focused on codec efficiency, device compatibility, latency, power consumption, and resilience to poor networks. AV1 can reduce bitrate by at least 20% versus H.264/AVC while preserving quality, especially below 100 kbps and for screen content. However, making it practical for mobile video calls required low-complexity encoding, careful decoder selection, and systems designed to avoid freezes caused by bitrate spikes and packet loss. ## Why Meta Adopted AV1 for RTC - AV1 delivers comparable visual quality at substantially lower bitrates than H.264/AVC. - Offline testing showed at least a 20% bitrate reduction on low-end and mid-range devices under Meta’s product settings. - Lower bitrate is especially valuable in real-time calls, where network rates may fluctuate between 10 and 400 kbps. - At a 100 kbps limit, AV1 video remained much clearer than H.264/AVC, which appeared blurry. - AV1 is also well suited to screen sharing: - **Palette mode** efficiently represents frames with a limited number of colors. - **Intra-block copy** predicts repeated patterns within the same frame. - Both tools improve the readability of text and other computer-generated content. ## Challenges of Real-Time Video - RTC requires end-to-end latency below roughly 300 milliseconds; techniques common in video-on-demand, such as multi-pass encoding and extensive buffering, can introduce unacceptable delay. - Sudden bitrate increases can cause freezes. - Network bandwidth changes may require adjustments to resolution or frame rate. - Resolution changes generally require a key frame, producing a temporary bitrate spike. - Packet loss can trigger retransmissions or additional key frames, also increasing the risk of freezes. - Mobile devices must encode and decode video simultaneously, making power efficiency essential. ## Encoder Selection and Complexity - AV1’s advanced coding tools improve compression but can significantly increase encoding complexity. - An open-source AV1 encoder consumed 14% more power than H.264/AVC on a Pixel 8 during testing. - AV1 also used more memory, contributing to application crash regressions. - Meta therefore adopted an internal low-complexity AV1 encoder with power consumption comparable to H.264 baseline. - The encoder supports multiple presets: - Higher-complexity presets prioritize quality. - An ultra-low-complexity preset offers complexity comparable to H.264/AVC. - Meta selects the encoder preset according to device capabilities, allowing AV1 deployment beyond high-end phones. ## Decoder Selection - Although decoding is generally less demanding than encoding, AV1 decoding was still challenging for low-end mobile devices. - Initial tests found real-time decoding failures, video freezes, and audio/video synchronization problems on some devices. - Meta evaluated multiple open-source decoders and selected **dav1d** based on its power efficiency and reliability. Meta’s experience shows that AV1 adoption in RTC requires more than simply enabling a new codec. A practical deployment depends on device-specific complexity controls, efficient decoding, strict latency management, and mechanisms that prevent bandwidth changes or packet loss from interrupting calls.

Read original

Real Time Communication Av1 Video Codec Dav1d+4

lineMar 17, 20263 min readCurated summary

Integration of LINE App’s Multi-party Chat Features

LINE is consolidating its two multi-person chat types—temporary “Rooms” and long-term “Groups”—into a single Group Chat model. The change aims to simplify the user experience, make all chat features available everywhere, and reduce duplicated server and client resources. A gradual migration strategy is being used to avoid disruption. ## Two Original Chat Models - **Rooms** were designed for temporary conversations: - No room name was required. - Invited friends joined immediately without approval. - Features such as albums and notes were unavailable. - **Groups** were designed for long-term communities: - They had names and supported features such as group albums and notes. - Invitees had to accept or reject invitations before joining. - Users often created Rooms without realizing their limitations, then created a new Group later when they needed additional features. ## Reasons for Unification - Users found the distinction between Rooms and Groups difficult to understand. - Existing conversations could not be converted from Rooms into Groups, forcing users to abandon their conversation history. - Users frequently created multiple chats with the same members, causing: - Cluttered conversation lists. - Unnecessary data accumulation on servers. - Increased client and server resource usage. - The unified model standardizes behavior and features while retaining flexibility in how invitations work. ## Migrating Groups to Group Chats - LINE introduced new Group Chat APIs and used **dual reads** to maintain compatibility with existing Group APIs and storage. - The migration proceeded gradually: 1. The new API initially read Group data through a routing layer. 2. The number of Group Chats was progressively increased. 3. Eventually, only Group Chats were created. - Batch processing migrated all existing Group data. - After migration, LINE stopped dual reads and relied exclusively on the Group Chat model. ## Differences Between Rooms and Groups ### Invitation Mechanisms - Groups required invitees to explicitly accept or reject an invitation. - Rooms added people immediately when they were invited. - The unified creation flow lets users choose whether invitees should join immediately or confirm participation first. ### Feature Availability - Rooms lacked many Group features because they were intended to be temporary. - The new model is based on the Group architecture, so all newly created conversations support the full feature set, including future features. ## Improving Conversation Discovery - Users often created a new chat with the same participants instead of finding an older, inactive conversation in a long chat list. - The new creation workflow displays a hint when an equivalent existing conversation is found. - Users can then return to the existing conversation, reducing duplicate rooms and improving navigation. ## Migration Plans for Existing Rooms - Conversations created in current LINE versions are already Group Chats. - Groups created with older app versions are being converted server-side. - The remaining objective is to migrate existing Rooms so their participants can use the complete set of Group Chat features. The project is a long-term effort designed to minimize disruption while improving consistency and efficiency. Duplicate conversations with identical participants fell from 15% for Rooms to 0.78% for invitation-free Group Chats, demonstrating the practical impact of the consolidation.

Read original

Real Time Communication User Experience API Design Data Migration+2

discordDec 15, 2025Original article

Discord Update: November 6, 2025 Changelog (opens in new tab)

The November 2025 Discord update focuses on streamlining content creation and enhancing the user interface across both desktop and mobile platforms. By removing technical barriers for emoji management and reorganizing core navigation, the platform aims to create a more intuitive experience for community interaction and personal expression. These changes signify a push toward visual consistency and greater flexibility in how users present themselves across different server environments. ### Streamlined Emoji Creation * A new integrated editing screen allows users to crop and resize large images directly during the upload process, eliminating the need for third-party photo editors. * The Emoji Picker now includes an "Add Emoji" shortcut for users with server permissions, allowing them to upload and assign icons to specific servers without leaving the chat interface. * Discord has automated the technical requirements for emoji uploads, removing the need for users to manually adjust files to specific resolutions (128x128), file types (PNG), or size limits before importing. ### Desktop Navigation and Utility * The desktop Settings menu is undergoing a visual refresh and reorganization to improve discoverability and match the platform's modern design language. * Voice channels on desktop now feature an active timer, providing a visible indicator of how long a specific call has been in progress. * The "More" section at the bottom of the Settings list serves as the new hub for accessing the Changelog and other platform documentation. ### Personalization and Mobile Features * Users can now set Nameplates on a per-server basis, allowing for professional appearances in some communities while maintaining more casual aesthetics in others. * The Discord Shop is now fully functional on mobile devices, enabling users to purchase and send gifts, Avatar Decorations, and bundles directly from tablets or phones. * Enhanced tools within the Family Center provide parents and guardians with updated oversight features to better monitor and engage with their teens' digital experiences. Server administrators and active users should take advantage of the new emoji upload tools to refresh their custom icons with less effort, while multi-community users can leverage the per-server Nameplates to better tailor their digital identity to different social contexts.

Real Time Communication Mobile Development Image Processing Asset Management+3

lineAug 14, 2025Original article

Case Study: Improving Video (opens in new tab)

Engineers at LINE identified a recurring monthly degradation in video call quality, specifically in Japan, where packet loss increased and frames per second (FPS) dropped toward the end of each month. Investigation revealed that this pattern was caused by mobile ISP bitrate throttling once users exhausted their monthly data caps, which the existing congestion control mechanisms were failing to handle efficiently. To resolve this, the team improved their proprietary CCFS (Congestion Control based on Forward path Status) algorithm to more accurately detect these specific network constraints and maintain stable playback. ### Analysis of Monthly Quality Degradation * Data analysis showed a "monthly cycle" where video decoding FPS was highest at the start of the month and progressively declined toward the end. * This quality drop was specifically tied to an increase in video packet loss, which prevents normal decoding and results in stuttering or frozen frames. * Statistical segmentation revealed the issue occurred almost exclusively on 4G mobile networks rather than Wi-Fi, and was more pronounced in high-bitrate video calls than in voice calls. * The root cause was identified as mobile data plan policies; as users hit their monthly data limits, ISPs impose speed restrictions that create network congestion if the application continues to send high-bitrate data. ### Limitations of Standard Congestion Control * While the IETF RMCAT working group has standardized algorithms like NADA (RFC8698) and SCReAM (RFC8298), real-time two-way communication requires more sensitive response times than one-way streaming. * In two-way calls, even a one-second delay makes natural conversation difficult, meaning the system cannot rely on large buffers to smooth out network instability. * Existing mechanisms were not reacting fast enough to the rigid throughput limits imposed by carrier throttling, leading to packet accumulation in network queues and subsequent loss. ### The CCFS Proprietary Algorithm * LINE utilizes a custom-developed, sender-based algorithm called CCFS (Congestion Control based on Forward path Status). * Unlike older algorithms that rely on Round Trip Time (RTT), CCFS focuses on the "forward path"—the actual path packets take to the receiver—by analyzing feedback on packet arrival times and loss. * CCFS categorizes network status into four distinct states: Default, Probing, Throttled, and Competing. * The system monitors "delay variation"; when it detects a continuous increase in delay exceeding a specific threshold, it transitions to the "Throttled" state to proactively reduce bitrate before the queue overflows. ### Strategies for Quality Improvement * The team focused on refining how CCFS handles the transition into the Throttled state to better align with the artificial bandwidth ceilings created by ISPs. * By improving the sensitivity of forward path status monitoring, the application can more rapidly adjust its transmission rate to stay within the user's current data plan limits. * This technical adaptation ensures that even when a user's mobile speed is restricted, the video remains smooth, albeit at a lower resolution, rather than breaking up due to packet loss. To provide a high-quality communication experience, developers must account for external factors like regional ISP policies. Refining proprietary congestion control algorithms to detect specific patterns, such as monthly data-cap throttling, allows for a more resilient service that maintains stability across diverse mobile environments.

Real Time Communication Video Streaming Congestion Control Network Adaptation+4

lineJun 9, 2025Original article

We tested the video call quality (opens in new tab)

To optimize the LINE messenger’s communication performance, LY Corporation conducted an on-site call quality assessment in Thailand to analyze local network conditions and compare performance against rising competitors. The study concluded that while LINE offers superior visual clarity and higher bitrates than its rivals, this high-performance strategy requires a careful technical balance to prevent video freezing in unstable network environments. ### High Video Call Adoption in Thailand * Thailand exhibits the highest video call usage among LINE’s major markets, with video calls accounting for 30.43% of all 1:1 sessions—more than double the rate of Japan or Taiwan. * The surge in usage by competitors, specifically "Messenger A," has necessitated frequent benchmarking to maintain LINE’s market leadership and technical edge. * Thailand serves as the primary testing ground for any updates to video modules due to the local user base's preference for high-quality real-time visual communication. ### On-Site Quality Testing Methodology * The assessment was performed over five days by five engineers across high-traffic locations in Bangkok, such as Siam Paragon and Samron Market, using True and AIS 4G/5G networks. * Engineers focused on Quality of Service (QoS) metrics—including packet loss and jitter—to estimate the actual Quality of Experience (QoE) for users. * Baseline performance for LINE in Thailand was recorded at VGA resolution, with frame rates exceeding 20 FPS and an average latency of approximately 150ms. ### Bitrate Strategy and Performance Trade-offs * LINE utilizes a high-bitrate strategy, capping at 1Mbps on 5G and 600kbps on 4G, to deliver sharper, more defined images than Competitor A. * A "start-at-max" approach is used where LINE attempts to find and utilize the highest possible bitrate from the beginning of the call to ensure immediate high quality. * In contrast, competitors adopt a conservative bitrate strategy, starting low and increasing slowly to prioritize connection stability over visual fidelity. * The trade-off for LINE’s higher quality is an increased risk of "freezing"—defined as a single frame persisting for more than 200ms—when the network becomes congested or unstable. ### Technical Implications for Future Development * The relationship between bitrate and network stability remains a zero-sum trade-off; higher bitrates provide better clarity but increase the likelihood of packet delay and loss at the router level. * LINE’s engineering focus is directed toward optimizing the "initial bitrate" detection logic to ensure high quality without triggering network-induced lag in crowded urban environments. * Continuous tuning of the balance between peak visual performance and consistent playback remains the core challenge for maintaining service quality in the Thai market.

Real Time Communication Voip Quality Of Service Network Performance+3

discordJun 2, 2025Original article

Thank You for Ten Years (opens in new tab)

Discord is celebrating its tenth anniversary, marking a decade of evolution from a niche gaming communication tool into a global social platform for 200 million monthly active users. The milestone report highlights how the platform has shifted the social media paradigm away from algorithmic feeds toward intimate, "digital living room" environments. Ultimately, the data shows that integrated voice and video features are the primary drivers for long-form engagement, significantly increasing both session duration and user retention. ## Gaming Ecosystem and Engagement Metrics * Discord’s reach has expanded to 200 million monthly active users, with over 90% of the user base having played a PC, console, or mobile game within the last 30 days. * The platform supports a massive variety of content, with users engaging in more than 8,000 unique titles per month on PC alone. * Total monthly gaming time on the platform exceeds 2 billion hours, highlighting its role as a central hub for the global gaming community. * Technical integration of voice chat acts as a force multiplier for engagement; users stay in gaming sessions three times longer when connected via Discord voice. ## Social Dynamics and Multimedia Co-consumption * Social influence drives discovery and play, as 28% of users launch a specific game within one hour of watching a friend stream it via the platform. * The presence of a social circle dramatically impacts performance and endurance, with gameplay sessions lasting seven times longer when users play with friends. * The platform has successfully transitioned into a general-purpose hangout space; after gaming ends, 66% of users remain to watch videos, 59% listen to music, and 49% watch movies or shows together. * 92% of users utilize voice channels simultaneously while gaming, indicating that the platform functions as a secondary layer to the primary gaming experience. ## The Architecture of Small-Scale Socializing * Discord has redefined digital interaction by prioritizing "micro-communities" over mass broadcasting, with 90% of all activity occurring in small, intimate servers. * Communication remains focused and personal, evidenced by the fact that the average voice call consists of only four participants. * Users are increasingly tribal but focused, typically rotating their time between three different friend-based servers per month. * This structure replaces traditional social media "doomscrolling" with active participation, mimicking the feeling of physical presence through low-latency voice and video communication. As Discord enters its second decade, its trajectory suggests that the future of social tech lies in facilitating high-quality, small-group interactions rather than massive public feeds. For developers and creators, the takeaway is clear: community stickiness is best achieved by building tools that allow users to seamlessly transition between active tasks, like gaming, and passive co-consumption of media.

Real Time Communication Voip Streaming Instant Messaging+3

discordApr 22, 2025Original article

Discord Appoints Humam Sakhnini as Chief Executive Officer (opens in new tab)

Discord has appointed former Activision Blizzard executive Humam Sakhnini as its new CEO, effective April 28, 2025, marking a significant transition from founder-led management to veteran industry leadership. Co-founder Jason Citron will move into an advisory role while remaining on the Board of Directors, and co-founder Stanislav Vishnevskiy will continue his tenure as Chief Technology Officer. This leadership shift is designed to accelerate Discord’s commercial scaling and deepen its integration within the global gaming ecosystem. **Leadership Transition and Industry Pedigree** * Humam Sakhnini brings over 15 years of high-level gaming experience, having most recently served as Vice Chairman at Activision Blizzard. * Sakhnini previously led King Digital Entertainment as President, where he managed record-breaking performance for massive titles such as *Candy Crush*. * His expertise spans managing multi-billion dollar portfolios including *Call of Duty* and *World of Warcraft*, positioning him to lead Discord’s efforts in professionalizing its business operations. * Jason Citron’s transition to Advisor follows a decade of building the platform from its inception to a cornerstone of digital communication. **Market Position and Financial Momentum** * Discord currently hosts more than 200 million monthly active users who generate 2 billion hours of gameplay each month. * The company has reported five consecutive quarters of positive adjusted EBITDA, signaling a transition from venture-backed growth to financial sustainability. * The platform remains the primary social infrastructure for multiplayer gaming, supporting thousands of individual titles through voice, video, and text integration. **Strategic Evolution of Revenue Streams** * While the core business has historically relied on the Nitro subscription service, the company is now diversifying into advertising and micro-transactions. * A renewed focus on "gaming roots" involves providing social infrastructure directly to game developers to help them engage their communities. * The new leadership aims to capitalize on modern revenue creation and customer acquisition strategies to better monetize the platform’s massive engagement metrics. This leadership change indicates that Discord is moving into a "growth and monetization" phase, prioritizing industrial-scale operations over early-stage product discovery. For developers and partners, this likely means a more aggressive rollout of developer tools and collaborative features designed to bridge the gap between gameplay and community management.

Real Time Communication Voip Monetization Gaming Industry+2